Hey everyone, I'm thinking of buying my buddy's 1985 Subaru GL-10 off of him for $300 (CAD), but there's a problem with it. He says that he's pretty sure it's the alternator. The problem is if you put a new battery in the car, everything will run smoothly, but the battery will die real fast. Could it be a problem with the computer stuff in the car (I'm a big n00b when it comes to cars, bare with me on the very n00bish terms) or would it be the alternator maybe? I really want this car, it will be my first car so I'm pretty excited about getting it. Any help would be great, thanks alot.

I would guess the problem is a drain. If the alternator is not charging there should be some warning lights on in the dash while the engine is running. I would first see if the lights work by turning the key to the run position without starting the engine. All the warning lights should turn on.

 

To see if there is a drain remove the negative battery lead and put a test light in series with the lead and the negative post, or use a ammeter. With everything off in the car the light should be very dim or not lit at all. The current shouldn't be more than about 80 milliamps if you use a meter. If there is a draw then pull fuses one at time to see which one causes a drop. That will be the path you need to check for a problem.

Thanks for the info Cougar. I've got no idea about cars, and I just looked up a bit about battery drain, and I found one place that said "starters have been known to short out at the solenoid and cause a constant drain to ground". Well, my friend's starter is kind of messed up, sometimes he has to hit it with a hammer a couple times to get it to work, so that would lead me to conclude that it's probably the starter that's screwed up, right? I'll do that test on it though to check out if it's draining from anything else though before I go to grab a new starter. Again, thanks alot for that info. :-p

In order for the starter to cause a current drain the starter solenoid would have to be engaged somehow. This kind of thing really doesn't happen, for the most part at least.

 

Current drains are usually traced to some accessory in the dash or under the hood. Sometimes the alternator can be the cause of the problem. If you work on the alternator be sure to disconnect the battery first because the output lead is hot to the battery.